1. Field of the Invention
The invention relates generally to aircraft control and, more particularly, to an improved aircraft control interface.
2. Description of the Related Art
Since the days of the Wright brothers, aircraft pilots have been faced with two major tasks. First, the pilot must accurately determine and constantly be aware of the current aircraft status, including location, direction, speed, altitude, attitude, and the rate of change of all of the above. Second, the pilot must be able to quickly and accurately control the aircraft to bring about a change in the above parameters to achieve a desired status of aircraft. In the early days of aviation, the first task was achieved by pilot awareness of visual and tactile stimulation. That is, the pilot looked around to see where he was, felt the wind pressure, and kept aware of acceleration forces pressing his body into the seat and around the cockpit. The second task was achieved by manually operating a mechanical pulley and lever arrangement to bend and pivot the horizontal and vertical control surfaces of the aircraft.
Initial developments to make the pilot's job easier included the provision of a magnetic compass to provide an indication of direction and pneumatic and mechanical instruments including altimeters, turn-and-bank indicators, etc., to provide indications of aircraft altitude and attitude. Subsequent refinements of these early instruments provided more accurate indications of location and altitude through the use of instruments and flight parameter displays such as gyro-compasses and flight directors. Various types of radio signals provided even more accurate determination of the aircraft location through the use of devices such as automatic direction finders (ADF), distance measuring equipment (DME), VORTAC, LORAN, and inertial reference systems (IRS).
Increases in aircraft performance over the years also increased the pilot's workload. To deal with this workload increase, various types of automation were introduced into the cockpit. One device, known as an automatic pilot (autopilot or AP) relieves the pilot of the necessity to provide continuous hands-on input to the control stick or yoke. When activated while the aircraft is in a stable configuration flying at a constant altitude, speed, and heading, the autopilot will sense the tendency of the aircraft to deviate from the established configuration and will automatically generate inputs to the control surfaces to return and maintain the aircraft in the preset configuration. This configuration will be maintained even in the face of changing wind conditions. More elaborate autopilots permit the pilot to enter data commanding a change in aircraft status, such as a command to climb to a pre-set altitude or turn to a preset heading.
Another type of automation provided in modern cockpits is the automatic throttle (autothrottle, or AT). The autothrottle will maintain a preset aircraft speed by varying the power setting on the engines as the aircraft climbs or descends.
A further refinement in cockpit automation occurred with the introduction of the flight management system (FMS). The FMS, in reality a type of specialized computer, includes a database of pre-stored navigation landmarks known as waypoints. A waypoint may either coincide with an existing ground landmark, such as an airport, or may represent an imaginary point in the sky where two radio signals intersect. The location of these waypoints in stored in the database. The pilot can enter a flight plan into the FMS by selecting a sequential series of waypoints through which the aircraft will travel.
Each waypoint is uniquely identified by a three-letter designator or short name. For example, the designator for Washington National Airport is DCA. A nearby waypoint used by aircraft navigating in the Washington area is HOAGE intersection, representing the intersection of two radial lines respectively emanating from navigation transmitters on the frequencies of 112.1 and 113.5 MHz.
Additional automation has been introduced into the cockpit through various types of automated systems and monitoring functions. Malfunctioning equipment or unsafe aircraft operating parameters will generate a variety of warning lights, audio signals, and even voice signals.
Although the present state of aircraft control systems has provided a vast improvement over the systems of previous eras, significant shortcomings still exist with respect to the goal of providing the safest possible aircraft operation. Many of these shortcomings relate to the vast proliferation of data which is supplied to the pilot and to the inefficient way in which this data is provided. For example, many cockpits have literally hundreds of warning lights scattered all over the cockpit. Furthermore, pilot input devices for specific functions are often dispersed in widely separated positions with insufficient thought given to pilot convenience. In addition, automated systems may provide increased convenience and efficiency in one area but increased pilot workload in another. For example, flight management systems often require large amounts of time to tediously enter desired waypoints and related parameters through a keyboard. Furthermore, this massive data entry process provides increased possibilities of error, sometimes with disastrous consequences. For example, improperly entering initial data into FMS at the beginning of a flight leg may have been a source of error leading to the disastrous course deviation and subsequent shooting down of Korean Airlines Flight 007.
Although automation in the cockpit can reduce the pilot's workload, thereby increasing safety, a countervailing consequence of increasing automation is a tendency to increase a pilot's sense of isolation from intimate control of the aircraft. To the extent the pilot does not have complete and continuous knowledge of the functions of the automated systems of the aircraft, there is a tendency for pilots to initiate undesirable control inputs which conflict with the inputs the aircraft is receiving from the automated systems, thereby compromising safety.
Another problem with existing systems is that they do not provide sufficient "situational awareness" to a pilot, thereby increasing the probability of accidents of the type referred to as "controlled flight into terrain" (CFIT). For example, current systems permit a pilot to command the autopilot to initiate a "Go to" command, causing the aircraft to immediately steer toward a designated location, without providing the pilot with adequate information regarding his current location.
In view of the above considerations, it is desirable to provide an improved flight information and control system which permit simplified flight planning and navigation procedures, reduced cost, reduced pilot workload, and improved safety.